Ohio Department of Education records show the number of accusations have tripled since 2007. The problems have included lewd text messages, inappropriate Facebook posts, physical threats and sex acts with students.

Depending on the type of misconduct reported, a teacher's inappropriate behavior toward a student is classified by the state as a case of conduct unbecoming or a sexual offense.

The number of conduct-unbecoming cases reported to the state increased from 250 in 2007 to 754 in 2011. However, specific sexual offenses investigated by the education department's Office of Professional Conduct have decreased since 2008.

Experts told The Dayton Daily News for a story Thursday that social media has allowed teachers more access to students outside the classroom.

"Because of social media we find that students will text their teachers and send them emails," said John Holbrook, assistant academic director and secondary education field placement coordinator for the University of Cincinnati. "They don't often think this might not be an appropriate way to communicate with a student."

Conduct unbecoming can be crimes or misconduct involving minors, school children, or a criminal conviction or misconduct that negatively reflects upon the teaching profession.

Inappropriate relationships can develop because "many of these kids have emotional needs and maybe for the first time in their lives there is someone who cares about them," said Charles Russo, Panzer Chair in Education at the University of Dayton and adjunct professor at its law school.

"These people are predators who can recognize kids with emotional weaknesses," he said. "It's not only against the law, it's seriously harmful for a teacher to take advantage of students."

Experts recommend that teachers and coaches not socialize with students after the designated hours they are supposed to be around each other.

"It has potential to open doors for problems," said Tom Henderson, superintendent of Centerville schools near Dayton, where a former teacher and golf coach was indicted in January on charges of sexual battery involving a former student.